Trump referred to Napolitano, a retired judge, as a “very talented legal mind” and of the claim he said: “I didn’t make an opinion on it.”

Both America’s National Security Agency (NSA) and the FBI have flatly denied allegations by Trump that he was bugged.

NSA director Admiral Mike Rogers insisted his organisation did not ask GCHQ to spy on the candidate during his campaign.

Asked if President Trump making “baseless” claims against British security services damaged the close relationship between the two nations, Admiral Rogers said: “I think it clearly frustrates a key ally of ours.”

Kevin Lamarque / Reuters

When pressed at US congressional hearings whether the incident would have a bad impact on security ties between the US and Britain, he said: “I believe that the relationship is strong enough...this is something we will be able to deal with.”

FBI director James Comey also denied the suggestion made by Trump in a tweet earlier this month that he had been bugged by Obama.

At the hearings, Comey said: “With respect to the president’s tweets about alleged wiretapping directed at him by the prior administration, I have no information that supports those tweets and we have looked carefully inside the FBI; the Department of Justice has asked me to share with you that the answer is the same for the Department of Justice in all its components.